* {
    margin: 0;
    padding: 0;
}
ul {
    list-style: none;
}
a {
    text-decoration: none;
}
.main {
    width: 720px;
    margin: 50px auto;
}
.tab {
    width: 320px;
    height: 38px;
    border: 1px solid #ccc;
    margin-bottom: -1px;
}
.tab > .active {
    border-top-color: red;
}
.tab > li {
    border-top: 4px solid #fff;
    float: left;
    height: 32px;
    line-height: 32px;
}

.tab > li > a {
    display: inline-block;
    width: 80px;
    height: 32px;
    text-align: center;
    color: #000;
}
.products {
    width: 720px;
    height: 505px;
    border: 1px solid #ccc;
    box-sizing: border-box;
    position: relative;
    overflow: hidden;
}
.products > img {
    display: none;
}
.products > .show {
    display: block;
}